ES2531906T3 - Procedure and apparatus for recovering spilled oil or other viscous liquid - Google Patents

Abstract

An apparatus for the recovery of a viscous liquid, comprising: (a) a rotary liquid recovery unit (10, 30); said liquid recovery unit (10, 30) having a surface with a pattern of a plurality of V-shaped grooves (14); said grooves (14) configured to collect and retain a viscous liquid (32) that comes into contact with said surface; and (b) a scraper (26) having an edge geometry complementary to said grooves (14), arranged to remove the viscous liquid retained from the surface of said liquid recovery unit (10, 30) (c); the apparatus being characterized in that said grooves (14) are defined by walls having a separation angle of approximately sixty degrees or less.

Description

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DESCRIPTION

Procedure and apparatus for the recovery of spilled oil or other viscous liquid.

5 CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the priority of the provisional US application Serial Number 60 / 673,043, filed on April 19, 2005, incorporated herein by reference in its entirety.

10 DECLARATION IN RELATION TO RESEARCH SPONSORED BY FEDERAL GOVERNMENT OR DEVELOPMENT

This invention was made with government support under Contracts No. 1435-01-04-RP-36248 and 1435-01-04-CT36287, granted by the United States Minerals Management Service (US MMS (U.S. Minerals

15 Management Service)). The Government has certain rights in this invention.

INCORPORATION BY REFERENCE OF MATERIAL PRESENTED IN A COMPACT DISC

Not applicable.

20 NOTICE OF MATERIAL SUBJECT TO COPYRIGHT PROTECTION

A portion of the material in this patent document is subject to copyright protection under the copyright laws of the United States and other countries. The copyright owner has no objection to the

25 facsimile reproduction by any of the patent documents or the disclosure of patents, as it appears in the United States Office of Trademarks and Patents of publicly available file or records, but otherwise reserves any copyright. The copyright owner does not waive any of his rights to have this patent document kept secret, including without limitation his rights under 37 C.F.R. § 1.14.

30 BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally pertains to the separation of fluids, and more particularly to the separation and recovery of viscous liquids from water or other fluids.

2. Description of the Related Technique

40 Mechanical recovery is the most frequently used oil spill response technique, and is a technique that is also used in industrial applications. This technique physically removes oil from the surface of the water, and the oil is usually floating on the surface of the water. Unlike other cleaning techniques, mechanical recovery can be applied effectively for the treatment of emulsified oils, as well as oils of varying viscosity. The main weakness of mechanical cleaning is the recovery rate. The

Mechanical recovery can take a long time and be very expensive when used on a large scale. Mechanical recovery may also require a large number of personnel and equipment, and each additional hour of cleaning can significantly increase the cost of recovery. Therefore, a more efficient recovery device could significantly reduce the cost of cleaning, as well as reduce the risk of oil reaching the coast.

50 An adhesion skimmer (oleophilic) is one of the most common types of mechanical recovery equipment. This type of skimmer is based on the adhesion of oil to a rotating surface of the skimmer. The rotating surface lifts the oil out of the water to an oil removal device (for example, a scraper, roller, etc.). The adhesion surface is the most critical element of the skimmer since it determines the efficiency of the recovery.

55 Various forms of skimmer, such as plush, belt, brush, disc and drum, have been developed to increase the efficiency of the skimmer.

Normally, two types of recovery surface patterns are used for oil adhesion skimmers. Smooth flat surfaces are used in drum, disc and belt skimmers. Drum skimmers

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and belt can also have a surface covered with brushes. The last configuration has an obvious advantage due to the much larger surface area (oil that covers each sow) and the formation of oil menisci between the bristles, but the difficulty of removing the oil from the brushes can result in a lower total recovery . The surfaces of the brushes tend to collect debris and water along with the oil, which can

5 affect the recovery efficiency and the oil transfer process. The smooth surface area of a drum, disc and a belt does not normally recover debris, but this configuration collects less oil than a brush surface due to the smaller surface area.

The oil spill recovery process has two important objectives. The first is to remove oil from

10 the surface of the water and the second is to remove the oil adhered to the recovery surface and transfer it to the collector. The efficiency of recovery depends on the achievement of these two objectives. In the case of a smooth surface, the amount of oil recovered is relatively low, but about 100% of it can be removed using a scraper. In the case of a brush surface and light to medium oils, the oil covers each sow and forms small meniscus between the sows, preventing them from draining back to the oil stain.

15 Unfortunately, the configuration of this surface does not allow you to individually scrape each sow and remove all the adhered oil. Therefore, a significant amount of oil remains on the surface after scraping and returns back to the oil stain, thereby reducing the total recovery rate.

A brush configuration works much more efficiently in high viscosity and semi-solid oils. In

20 In this case, the oil does not cover the bristles or penetrate into the brush. It simply rises from the water at the tips of the bristles and is physically transported to the collector. This process is not exactly related to oil adhesion and extension properties. This explains the ability of the surface of a brush to recover more debris than a smooth surface.

25 Therefore, the use of brushes increases the contact surface between the oil and the recovery device, and takes advantage of the effect of capillary forces for the collection of oil between the bristles. However, a disadvantage of the brush process is the fact that the brushes collect waste and water along with the oil, which can clog the pipes of the oil collection device. Another disadvantage is its inability to remove much of the oil attached to the brushes using scrapers, since they cannot scrape each brush

30 individually. An improvement has been sought through the use of porous mats (or similar structures) that cover the surface of the skimmer, allowing the oil to penetrate its matrix, rise from the water and be ejected by the rollers in the collection device. However, such improvements are intended to increase the volume of oil that can be recovered from the water per unit area of the recovery surface. Although such improvements allow a thicker oil film to form on the recovery surface, they do not allow scraping of all

35 recovered oil. On the contrary, belts and drums with smooth surfaces allow almost 100 of the adhered oil to be transferred to the manifold. However, the disadvantage of smooth recovery surfaces is that only a relatively thin layer can be formed on its surface and the total volume of recovered oil is relatively small.

40 To select the most efficient response to oil spills, it is important to understand the chemical and physical behavior of the spilled oil and how these characteristics change over time. The increase in viscosity and the formation of an emulsion are dynamic processes of particular interest. Petroleum products and oils from different fields have extremely diverse chemical properties and compositions. The viscosity of these products may vary in the range of

45 0.5 mPas to 100,000 mPas. The aging of the oil entails an additional complication for the prediction of the properties of the spilled oil and has important ramifications with respect to the appropriate recovery strategies. During the first twenty-four hours, some oils may lose 5% to 50% of light compounds. There will be a significant increase in oil viscosity, caused by evaporation of the lighter compounds and emulsification, in hours to a few days. Therefore, the oil that has to

50 recover does not have the same properties as the oil that has been poured. Existing types of skimmers are not adapted to the properties of the product to be recovered and can only recover oil within a certain range of properties. They are characterized by a specific "window of opportunity" - a period of time when this equipment can be used, which is largely determined by the properties of the oil (viscosity in particular). Outside that period of time, response measures with this equipment may arrive

55 to be ineffective.

BRIEF SUMMARY OF THE INVENTION

The present invention pertains to the separation of viscous liquids from water or other liquids, for example,

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increasing the recovery efficiency of an adhesion skimmer (oleophilic). The invention is defined by the appended claims. One aspect of the invention is to modify the surface of a rotary liquid recovery unit in an adhesion skimmer with a groove pattern that increases recovery efficiency.

5 The characteristics of an adhesion skimmer that can significantly increase oil recovery efficiency can be summarized as follows:

(a) You should maximize the collection surface for a given width of the recovery surface (for example, drum, belt or disc).

(b)

 A configuration that allows the formation of oil menisci is desirable, since this allows the thicker layer of oil to recover and slows the oil drain back to the oil spill.

(C)

It should be able to remove about 100% of the oil adhered to the recovery surface using the scraper.

15 (d) It must be able to adapt to changes in the properties of the oil, as it ages over time, and be able to efficiently recover an oil with a wide range of properties. This will allow the use of the same recovery surface for the entire period of the recovery process.

The present invention addresses these characteristics by means of a surface pattern of the unit of

20 recovery with a plurality of grooves as claimed, which are configured to allow the formation of menisci and provide a space for the oil to accumulate.

The inventors have pointed out that the surface pattern of the rotary liquid recovery unit in a skimmer with narrow "V-shaped" grooves or channels will maximize the surface of the unit of

25 liquid recovery. Depending on the angle and depth of the grooves, the surface can be increased several times for the same recovery surface width. In addition, this configuration allows meniscus to form in the depth of the groove, thereby increasing the amount of oil recovered and slowing the oil drain. The variation of the groove opening with the groove depth allows it to be used efficiently in oils with a wide range of viscosities. The most oils

Light 30 will be collected in the depth of the groove, while the viscous oils can be collected in a wider part of the groove that allows water to drain into the deepest part of the groove. The scraper is then configured to match the contour of the recovery surface. When V-pattern surfaces with a corresponding scraper are used, about 100% of the adhered oil can be removed and transferred to the oil pan.

It should also be noted that, according to embodiments that are not part of the claimed invention, the oil withdrawal angle of the oil spill has an effect on the formation and thickness of the adhered oil film. If the oil is removed at an acute angle (0-90 degrees), it forms a thicker film on the surface because the effect of gravity is reduced by the presence of the recovery surface under the film. In this

40 case, the oil drain is relatively slow. If the oil is removed at an angle greater than 90 degrees, the force of gravity is not compensated by the substrate and the surface oil drain rate is significantly higher. This leads to the formation of a much thinner oil film and, therefore, a lower recovery efficiency. Although a V-patterned surface (or any recovery surface therefore) is more efficient when used to remove oil at angles of less than 90 degrees to maximize the thickness of the

45 recovered film, a withdrawal angle of 90 degrees and higher can also be used.

In addition, when the oil is rotated below the surface of the water, the hydrostatic difference between the oil and the water causes it to impact the recovery surface quite well. This very floating oil adheres firmly to the recovery surface, thus allowing the oil to spin out of the water faster

50 than with other devices.

Accordingly, one aspect of the present invention is a way of increasing the recovery efficiency of the floating oil (or any other viscous liquid) by modifying the surface geometry of the liquid recovery unit in an oleophilic skimmer.

Another aspect of the present invention is a scraper that has a surface geometry that is complementary to the grooved geometry of the recovery surface and allows the oil to be scraped off the recovery surface and transferred to the manifold.

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Another aspect of the invention is that, when the liquid recovery unit (e.g. drum, disc or belt) rotates to the viscous liquid, the grooves help keep the viscous liquid on the surface of the liquid recovery unit . In other words, the viscous liquid does not escape from the grooves to the sides when the liquid recovery unit pushes the liquid under water as it is being retained by the

5 sides of the groove. In the case of a smooth drum or belt, water under the viscous liquid layer will push it up, so the viscous liquid can escape laterally below the drum or belt and will not remain in contact with the surface.

In one embodiment, an apparatus for recovering a viscous liquid according to the invention comprises

A rotary liquid recovery unit having a recovery surface with a pattern of a plurality of grooves that are configured as cited in the claims for collecting and retaining a viscous liquid that comes into contact with the recovery surface, where they form meniscus and the viscous liquid accumulates in the grooves.

In one embodiment, the grooves have a depth of approximately five inches or less. More preferably, in a beneficial embodiment, the grooves have a depth of about an inch or less.

In an embodiment of the claimed invention, the angle of separation is approximately sixty degrees or less. In another embodiment of the claimed invention, the separation angle is approximately thirty degrees.

or less. In said embodiments, the angle of separation slows the drainage of the viscous liquid from the grooves.

In an embodiment of the claimed invention, the liquid recovery unit has a first and second ends, a longitudinal central axis that extends between the first and second ends, and a central radial axis that

25 is orthogonal to the longitudinal axis, and the grooves substantially align with the central radial axis. In another embodiment, the grooves move angularly from the central radial axis at an angle less than about ninety degrees.

In accordance with the claimed invention, the apparatus additionally comprises a scraper having a

30 edge geometry complementary to the grooves whereby the scraper is adapted for the removal of the viscous liquid collected by the liquid recovery unit.

Additional aspects and embodiments of the invention will become apparent in the following parts of the specification, where the detailed description is intended to fully disclose the preferred embodiments

35 of the invention without placing limitations on this.

BRIEF DESCRIPTION OF THE VARIOUS VIEWS OF THE DRAWING OR DRAWINGS

The invention will be more fully understood by reference to the following drawings for illustrative purposes only:

Figure 1 is a schematic partial side view of a skimmer with an embodiment of a corrugated drum-type liquid recovery unit in accordance with the present invention.

Figure 2 is a cross-sectional view of the liquid recovery unit shown in Figure 1 taken through line 2-2.

Figure 3 is a cross-sectional view of the liquid recovery unit shown in Figure 1 taken through line 3-3 and illustrates the liquid recovery unit in relation to a scraper for

50 remove the oil collected on the recovery surface.

Figure 4 is a top plan view (bottom figure) of an embodiment of the surface of the liquid recovery unit shown in Figure 1 and a cross-sectional view (top figure) taken through the line AA of the top floor view.

Figure 5 is a partial cross-sectional view of an embodiment of the surface of the liquid recovery unit shown in Figure 1,

Figure 6 illustrates the oil recovery process according to the present invention.

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Fig. 7 is a schematic partial side view of a skimmer with an embodiment of a belt type corrugated liquid recovery unit according to the present invention.

5 Figure 8 is a schematic partial side view of an alternative embodiment of a skimmer with a belt type corrugated liquid recovery unit shown in Figure 7.

Figure 9 is a schematic partial side view of a skimmer with an alternative embodiment of the drum-type fluted liquid recovery unit shown in Figure 1.

10 Figure 10 to Figure 12 are schematic side views of the liquid recovery unit shown in Figure 1 located at various depths in the water according to embodiments that are not part of the claimed invention.

Figure 13 to Figure 19 are partial cross-sectional views of various configurations of grooved surfaces that can be employed in a liquid recovery unit according to embodiments that not all are part of the claimed invention.

Figure 20 and Figure 21 are side and plan views, respectively, of a flat test surface for a liquid recovery unit.

Figures 22 and 23 are side and plan views, respectively, of a ribbed test surface for a liquid recovery unit with straight walls at ninety degree angles.

Figure 24 and 25 are side and plan views, respectively, of a ribbed test surface for a liquid recovery unit with straight walls at angles of sixty degrees.

Figures 26 and 27 are side and plan views, respectively, of a ribbed test surface for a liquid recovery unit with straight walls at thirty-degree angles.

Figure 28 and 29 are side and plan views, respectively, of a ribbed test surface for a liquid recovery unit with curved grooves having small diameter curves.

Figures 30 and 31 are side and plan views, respectively, of a grooved test surface for a liquid recovery unit with curved grooves having large diameter curves.

Figure 32 is a graph comparing the drainage curves for the test surfaces shown in Figure 20 to Figure 31.

40 Figure 33 is a graph comparing the oil recovery curves for the flat and V-shaped test surfaces shown in Figure 20 to Figure 27.

Figure 34 is a graph showing the maximum initial oil recovery and final oil recovery after drainage as a function of the angle of the groove.

45 Figure 35 is a graph showing the results of Endicott crude oil recovery tests at an oil thickness of 25 mm at 25 ºC-30 ºC.

Figure 36 is a graph showing the results of the recovery tests for HydroCal 300 at an oil thickness of 25 mm at 25 ºC-30 ºC.

Figure 37 is a graph showing the recovery efficiency of aluminum drums at 25 ° C-30 ° C.

Figure 38 is a graph showing the recovery efficiency of aluminum drums at 10 ° C-15 ° C.

55 Figure 39 is a graph showing the effect of temperature and film thickness on the recovery efficiency of HydroCal.

Figure 40 is a graph showing the effect of temperature and type of oil on the efficiency of

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aluminum drum recovery.

DETAILED DESCRIPTION OF THE INVENTION

5 Referring first to Figure 1 to Figure 5, an embodiment of the invention is shown in the context of a rotary fluid recovery unit 10 that is typically found in an adhesion skimmer (oleophilic). Adhesion skimmers are well known in the art and their details will not be described here. Such skimmers are available, for example, from companies such as Elastec / American Marine, Inc.

10 In the exemplary embodiment shown, the recovery surface 12 of the recovery unit (eg, drum, disc or belt) 10 has a pattern with a plurality of grooves 14. The grooves 14 are arranged around the circumference of the recovery unit and are substantially parallel to each other between the ends 16, 18 of the skimmer 10. In addition, in the embodiment shown, the grooves have a depth "d" and a wall angle "" that contribute to the ability of the apparatus to recover a viscous liquid. In

In particular, the recovery of the viscous liquid is more effective with narrow grooves instead of wide grooves, provided that the grooves are wide enough to allow penetration of the grooves by the viscous liquid. In addition, an angle a between walls 20, 22 of approximately thirty (30) degrees or less is preferable, although wider angles (but preferably less than approximately sixty (60) degrees) are also within the scope of the claimed invention.

In addition, a groove depth of approximately one inch or less is preferable, although deeper grooves, such as approximately five inches or less, may also be employed. It should also be noted that by making the grooves shallower and therefore less wide at the same groove angle, more grooves can be adapted for the same width of the drum.

Therefore, as can be seen from the foregoing, the embodiment of the apparatus shown in Figure 1 to Figure 5 includes a rotating drum 10 having an outer surface 12 and a plurality of grooves 14 on the outer surface. Each of the grooves 14 has a pair of separate walls 20, 22 that define the shape of the groove, and each of the grooves has an internal term 24 delimited by the separate walls that defines the depth of the groove. Consequently, each of the grooves has a depth

30 "d", an outer width "w", and an angle  such that when the drum 10 is brought into contact with a viscous liquid, the liquid accumulates in the grooves for recovery. The combination of the depth of the grooves and the angle of the wall provides the formation of a meniscus and the accumulation of the viscous liquid on the internal surface and the walls of the grooves, thus providing an increase in the capacity of liquid collection .

In a preferred embodiment, the depth of the grooves is approximately one inch or less, and the angle of separation between the walls of the grooves is approximately thirty degrees or less. It will be appreciated that the angle shows the drainage of the viscous liquid from the grooves.

In the embodiment shown, the drum has a first end 16 and a second end 18, a longitudinal central axis "LA" extending between the first and second ends, t a central radial axis "RA" that is orthogonal to the longitudinal axis . Here, the grooves are substantially aligned with the central radial axis. Although alternative embodiments may include grooves that move angularly from the central radial axis at an angle less than approximately ninety (90) degrees, the displacement of the grooves in that manner can make it difficult to

45 alignment of the scraper 26 with the grooves for the removal of the liquid.

As illustrated in Figure 6, the use of this form for the recovery surface increases the surface in contact with the liquid 28 to be recovered and uses capillary forces to allow greater volumes of liquid to be collected in the confined space of the grooves. for recovery.

50 It will be further appreciated that the drum, the belt or the disk can be tilted at an angle in relation to the water. For example, referring to Figure 7 and Figure 8, side views of belt type skimmers 30 are schematically illustrated, where the skimmer of Figure 7 rotates in a clockwise direction by raising the oil out of the water, and the skimmer in the Figure 8 rotates counterclockwise transporting oil under water and by

55 on the belt towards the scraper. Another mode of recovery is for the belt, in order to transport oil under water and collect it in a pool behind the belt from where the oil can be recovered, for example, by a suction skimmer. According to the embodiments that are not part of the claimed invention, the angle of inclination in relation to water 32 is preferably ninety degrees or less, but it is also possible to remove viscous liquids at other angles.

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From the above, it will be appreciated that the system is basically three-dimensional. There may be an orientation angle of the grooves on the recovery surface and there may be another orientation angle of the recovery surface itself relative to the surface of the water.

5 With particular reference now to Figure 1 and Figure 3, after the collection of the viscous liquid on the surface 12 of the liquid recovery unit 10, according to the claimed invention, a scraper 26 is used to remove the liquid viscous for recovery and disposal. In order to facilitate the removal of the viscous liquid, the scraper used with the present invention has a matching edge geometry.

10 substantially with (for example, the surface geometry of the skimmer is substantially complementary to) so that the viscous liquid can be scraped off the recovery surface and transferred to the manifold 34. The scraper must closely correspond with the recovery surface for substantially scraping Complete and efficient.

15 Referring to Figure 1 and Figure 9, it will also be appreciated that the direction of rotation of the skimmer 10 can be clockwise or counterclockwise. More particularly, the rotation of the recovery surface may be in the direction of removal of the oil from the water, or in the opposite direction of immersion of the oil in water and transport under the recovery surface. The particular direction of rotation selected will, of course, influence the position of the scraper 26 and the manifold 34.

In addition, as illustrated in Figure 10 to Figure 11, the depth of the skimmer 10 in the water 32 may vary. Figure 10 shows approximately half the diameter of the skimmer located above and below the waterline. Figure 11 and Figure 12 show approximately one third below the waterline and approximately two thirds below the waterline, respectively.

The geometry of the invention of the skimmer surface can be used in any case when separation based on liquid adhesion is used. The invention is expected to improve the efficiency of oleophilic skimmers that collect oil (or any other viscous liquid) from the surface of the water. The most efficient way to use this invention is to replace the existing surface of adhesion skimmers with belts, discs or

30 drums made of an oleophilic material and modified with the surface geometry described herein. More viscous liquid can be recovered if the withdrawal angle is less than about 90 degrees. The speed of rotation of the belt / drum must be fast enough to prevent oil drainage to the recovery surface. The use of the most reasonably available oleophilic material is preferred to improve recovery efficiency.

In the embodiment described above, the V-shaped grooves are modeled on the surface of the skimmer. However, other forms that not all constitute part of the claimed invention may also be employed, as illustrated by way of example in Figure 13 to Figure 19. The modified V-shaped configurations of Figure 13 and Figure 17 have external flat surfaces that make it easier to place

40 the skimmer on a hard surface without damage. Other configurations of selected grooves will depend on the properties of the liquid to be recovered.

It will be appreciated that a surface with V pattern as cited in the claims maximizes the surface area of the drum. Depending on the angle and depth of the grooves, the surface area may be increased several

45 times for the same width of the recovery surface. This also allows meniscus to form in the depth of the groove, increasing the amount of oil recovered and slowing the oil drain. The variation of the groove opening with the groove depth allows a wide range of viscosities to be used more efficiently on oils. The lighter oils will be collected in the depth of the groove, while the viscous oils can be collected in a wider part of the

50 groove that allows water to drain into the deepest part of the groove. The scraper must be made to match the recovery surface. If V-pattern surfaces with a corresponding scraper are used, about 100% of the adhered oil can be removed and transferred to the oil pan.

It should also be appreciated that in accordance with the embodiments that are not part of the claimed invention, the

The oil withdrawal angle of the oil spill affects the formation and thickness of the bonded oil film. If the oil is removed at an acute angle (0-90 degrees), it forms a thicker film on the surface because the effect of gravity is reduced by the presence of the recovery surface under the film. In this case, oil drainage is relatively slow. If the oil is removed at an angle greater than 90 degrees, the force of gravity is not compensated by the substrate and the surface oil drain rate is significantly higher.

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This leads to the formation of a much thinner oil film and, therefore, a lower recovery efficiency. Although a 90-degree withdrawal angle allows more efficient oil recovery than a wider angle, a V-pattern surface (or any recovery surface can therefore be used) to remove the oil at angles of less than 90 degrees for Maximize the thickness of the recovered film.

5

Example 1

(Test Surfaces)

10 Several surface patterns were manufactured from aluminum plates to study the effect of the surface pattern on recovery efficiency. The test surfaces studied are illustrated in Figures 20 to 31. A flat test surface is illustrated in Figure 20 and Figure 21, test surfaces having grooves with a V-shaped cross section are illustrated in Figure 22 to Figure 27, and test surfaces having grooves with a rounded cross-section are illustrated in Figure 28 to Figure 31.

It will be appreciated that the surface area can be significantly increased by introducing the grooves with more acute angles, as illustrated in Table 1. The surface area of the grooved side can be increased up to three times if a flat surface is replaced by a surface with grooves of 30 degrees. This will not translate directly to a recovery rate 3 times higher, since the oil collected at the depth of the

20 groove is fixed to two sides of the groove at the same time. However, the V-pattern surface has a significantly larger surface area compared to the flat surface and, therefore, will allow a higher oil recovery rate for the same drum / belt width.

In addition to the V-shaped grooves, there may also be other configurations, as shown in the

Figure 28 to Figure 31. Some configurations may lend themselves to easier machining in a drum or belt skimmer and, therefore, all possible geometric configurations are being explored. Additional research on the advantages and disadvantages of each geometry will be useful.

Example 2

30 (Investigation Procedure)

Experiments were carried out in the temperature controlled room at 25 ºC (1 ºC). The test procedure was similar to the immersion and withdrawal test described in Jokuty, P., et al., "Oil adhesion testing - recent

35 results ", Proceedings from the Nineteenth Arctic Marine Oil spill Prog. Tech. Seminar, Canada (1996).

Fast oil recovery was done using a stepper motor. The experiment setup included a computer, a scale connected to the computer, a beaker to hold water and oil, a test surface, a sample holder, and a motorized stand to move the sample holder in

40 vertical

The test samples were previously cleaned with soapy water, ethanol and deionized water, blow dried in a stream of nitrogen and left in the temperature controlled room for at least 24 hours before the test. A beaker was filled with 50 ml of filtered seawater from the Santa Canal

45 Barbara (salinity of approximately 33.6 ppt). Then, 5 ml of HydroCal 300 was carefully added on top of the water surface. The beaker was installed in the balance connected to the computer.

A test surface 100 was coupled to a sample above the oil surface using a knob

50 attached 102. The sample holder could be moved vertically using a programmed motor so that the test surface could be submerged in the oil-water mixture in 20 mm and then removed. The withdrawal speed was 74 mm / s. Once the surface with oil was removed from the beaker, the balance detected the maximum oil loss and then generated the signal to trace the increase in the mass of oil in the beaker caused by the drain of oil from the plate and the drops of oil that fall back to the glass of

55 precipitates From the shape of these curves, the effect of recovery and the properties of the oil were analyzed. Five to ten tests were performed for each test surface to ensure the accuracy of the data. New oil was used in each test.

Example 3

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(Results and Analysis)

Drainage curves are presented for the various patterned surfaces in Figure 32, compared to a

5 flat surface. The initial weight of the beaker with seawater and the oil layer was reduced to zero. Therefore, oil recovery was measured as a negative change in mass. The zero moment represented the beginning of the withdrawal process. In approximately four seconds the test surface was completely removed from the beaker. That moment represented the maximum mass of oil adhered to the test surface, before the oil began to drain back into the beaker in the form of oil drops. After

10 approximately twenty-five seconds, the oil drain stopped in most cases. The most recovered final was discovered by averaging the data in the final plateau section of the curve.

The data presented in Figure 32 shows that there is a significant difference between the amount of oil recovered by the patterned surfaces. The flat surface data had to be corrected to take into account the fact that the flat surface had a lower surface area of the bottom than the corrugated surfaces. The corrugated surfaces had a comparable size of the bottom areas. The calculation of the weight of the fall corresponding to the surface area of the bottom of the corrugated samples allowed to move a curve for a flat sample to a new position that allows comparing the recovery properties of the recovery surfaces and excluding the effect of the presence of the drop in the bottom of the samples after the withdrawal. Figure 32 shows that recovery efficiency can be folded with a 30 degree surface pattern instead of a flat surface. Recovery increases with a downward angle, but at some point there is a limit to the amount of oil in the groove, which was not explored. It appeared that grooves with rounded cross sections were less efficient than grooves with a triangular shape. The effect of the angle of the groove for the V-shaped grooves is presented in Figure 33.

25 It was found that a downward angle increases oil recovery for a given oil.

Figure 34 summarizes the initial (maximum) oil removal from the water surface, and the final removal after the oil drains back into the beaker, for the various surface patterns. The upper line corresponds to the maximum amount of oil that can be recovered at a withdrawal rate of 74 30 mm / s, while the lower line corresponds to the final oil that remains on the surface after drainage. The first illustrates recovery at faster speeds and the latter illustrates recovery at a very slow speed. Total recovery efficiency increases with a descending groove angle since a smaller angle retains a greater meniscus in the groove and slows the oil drain. However, for very viscous oils and emulsions, the groove opening should be wide enough for the

35 oil / emulsion enters the groove. Therefore, there is a minimum groove angle that may depend on the properties of the oil. Grooves with a smaller angle also increase the surface area of the drum by unit width allowing more surface oil to be set as illustrated in Table 1.

It should be noted that the rotational speed of the skimmer can also have an important function. The effect of

40 the grooves on the oil recovery by means of drums in a large-scale test may be even more pronounced than that observed in the laboratory and the oil recovery efficiency may be greater, due to the difference in the hydrodynamics of the process. The recovery speed should be high enough to bring the maximum amount of oil collected to the scraper and prevent it from draining. A limiting factor may be the drag of water at high speeds, which can break the oil film. Once the movie

When the oil breaks, the contact between the oil and the recovery surface at very high rotational speeds can be lost, resulting in a decrease in recovery. High rotation speeds can also emulsify the oil, which results in increased water withdrawal and can reduce the total oil recovery rate. The desired rotation speed can be determined experimentally with a large-scale test, and is likely to depend on (1) the surface material; (2) the

50 withdrawal angle; (3) the properties of the oil; and (4) the temperature.

Accordingly, in the present invention, the recovery surface is modeled with grooves as cited in the claims, on a small scale in a configuration that allows the meniscus to form, as well as the oil "clustering" on the bottom (internal term) of the groove, providing a lot quantity

55 more oil recovered than oil that simply covers a surface in a layer. In addition, when designing these small grooves so that they have wall angles of approximately thirty degrees or less, there is a slowdown of the viscous liquid drained out of the groove that can be stopped between the capture in the water and the rotation with respect to the cleaning device.

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The present invention increases contact with the viscous liquid to be recovered, which in itself increases the volume of recovered fluid. It also uses the capillarity effect, allowing larger volumes of liquid to be collected in the confined space of the grooves and, therefore, to be recovered. The corrugated structure allows the skimmer to be used efficiently in liquids of different properties. The less viscous liquids will be collected in the narrow and deep part of the grooves; Liquids with higher viscosity may not be able to penetrate so far and adhere to the walls of the grooves at their widest part, allowing the less viscous liquid (water) to drain into the deep part of the groove. The invention allows a thicker film of liquid to form in the recovery device and to be removed. It also ensures that about 100% of the recovered liquid can be removed from the recovery surface (scraped off)

10 to the collection device. A scraper made of oleophobic material with the shape corresponding to the geometry of the grooves should be used for these purposes.

Example 4

15 (Field Tests)

Field-scale tests were conducted at the National Test Facility on response to Ohmsett oil spills. Novel materials and surface patterns were used to retrofit the recovery drums in an existing skimmer in the Ohmsett. These drums were installed in a skimmer body

20 conventional and were used to recover an oil stain while monitoring the main recovery parameters. The effect of each design or the operational variable on oil recovery efficiency was evaluated.

Materials:

25 Five materials (aluminum, polyethylene, polypropylene, neoprene and Hypalon) were used to make smooth drum surfaces. In addition, three drums had a grooving pattern (30º angle, 1 inch deep) machined in aluminum and coated with neoprene and Hypalon. An aluminum drum was left uncoated. A corresponding scraper was made with the ribbed pattern. Figure 1 illustrates two corrugated drums.

30 In order to eliminate the variables that could be introduced using different skimming systems, a drum-type skimmer (Elastec Minimax) was used for all tests. This skimmer uses a drum that rotates through the oil layer. Adhesion oil is subsequently removed using a plastic shovel to an on-board recovery drain.

35 Test Oils:

Diesel, Endicott (an Alaskan crude oil) and HydroCal 300 (a lubricating oil) were used during Ohmsett tests to study the effect of oil properties on recovery efficiency. These oils

40 have significantly different properties as illustrated in Table 2, which allowed the recovery surfaces to be tested on a wide range of possible recovery conditions. Diesel was only tested during the second test, at cooler temperatures, since it was subsequently added to the protocol.

Test Procedure

45 The tests in the Ohmsett were carried out in two days. During the first day, the average ambient temperature was approximately 25 ºC-30 ºC. During the second day, the average ambient temperature was approximately 10 ºC-15 ºC. The objective was to simulate an oil spill in hot and cold water conditions, to determine the effect of the oil's temperature and viscosity on the spill recovery efficiency

50 total oil

During the tests, a skimmer assembly was secured in the center of a test tank located on the Ohmsett installation platform. The thickness of the stain was controlled so that it remained at a predetermined level throughout a given test. According to the oil skimmer recovered oil from the tank

55 test, more oil was pumped from the oil tank at the same speed. In this way, real-time control of stain thickness can be controlled at 20%. Most of the embodiments were made for 5 minutes, although some were made for less time (3 minutes) if the conditions were very similar.

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The rotation speed of the oil skimmer drum was controlled with a hydraulic system equipped with the Elastec MiniMax system. Three rotation speeds (30, 40 and 70 rpm) were used for most of the tests. The first two speeds represented the regular operating conditions of a drum skimmer, with minimal skimming of free water. The 70 rpm speed represented the rotation speed

5 maximum that was achieved by this particular skimmer. At this rate, more oil was collected, but more free water was dragged through the skimmer, particularly for thinner oil stains (10 mm). A higher rotation speed also emulsified the oil greatly.

At the end of each test embodiment, the total amount of liquids (oil and water) was measured, the water was collected from the

10 background for several minutes until no more free water was evident, and the remaining oil, or oil emulsion, was collected to measure the water content in the Ohmsett's laboratory. These data, along with the recovery time, were used to establish recovery rates and efficiency.

Test scores:

15 The recovery efficiency of various skimmer drums tested with Endicott and HydroCal 300 (for a pouring thickness of 25 mm) during the first phase of the experiments is presented in Figure 35 and Figure 36. The ambient temperature during the first test varied from 25 ° C-30 ° C. Oil recovery rates in gallons per minute (GPM) were estimated from the calculation of oil recovered per unit time. Free water and

The water emulsified in the recovered oil was subtracted from the volume of the total recovered liquid. These figures show that there is approximately a 20% difference in the recovery efficiency of smooth drums coated with various materials.

The difference between smooth and fluted drums was much more significant. For both oils, the drums

25 flutes recovered more than twice as much oil as the smooth ones. A slight decrease in recovery rates at 70 rpm can be explained by the greater amount of free water collected by the drums, thus decreasing the net amount of oil recovered.

At an oil spill thickness of 25 mm, the corrugated drums recovered an amount of water that was

30 comparable to the amount of water recovered by the smooth drums. Some deviations in the results may have been caused by the fact that some embodiments were made with oil that was emulsified during the previous embodiment. The water content of some recovered oils rose to 8%. It was observed that HydroCal easily emulsified and had a higher water content than Endicott oil, which had an influence on the total recovery of free and emulsified water.

35 A comparison of the effects of the type of oil, the thickness of the oil spill and the surface pattern of the drum on the recovery efficiency is summarized in Figure 37. All the data presented correspond to fluted and smooth aluminum drums. These data were collected during the first tests at a temperature between 25ºC-30ºC. Decrease in film thickness of HydroCal oil thickness from 25 mm to 10 mm

40 led to a significant decrease in recovery efficiency. This was especially pronounced in the case of corrugated drums. An increase in oil thickness from 25 mm to 50 mm did not increase recovery rates. Although Figure 37 shows some decrease in recovery efficiency to 50 mm, it was most likely due to the fact that the oil used for these tests was slightly emulsified and had an initial water content of approximately 6%. This slightly reduced the total oil recovered.

When the corrugated aluminum drum was tested with recent HydroCal oil at 40 rpm and 50 mm, the result was similar to the recovery efficiency of the same drum at an oil thickness of 25 mm. This data is represented by the only star-shaped data at the top of the graph.

Figure 37 shows that the amount of oil recovered by the corrugated drums was two (2) to three (3) times

50 greater than that recovered by smooth drums. It was also discovered that the type of oil had a significant effect on recovery efficiency, mainly due to the difference in viscosity.

The effects of oil type, film thickness and drum surface pattern on the recovery efficiency observed during the second tests are summarized in Figure 38. For a thickness of the spillage of

55 10 mm oil, there was almost no difference between smooth and fluted drums. The surface pattern is much more effective for thicker oil stains. At an oil thickness of 25 mm, the grooved pattern proved to be extremely efficient for Endicott and diesel oil, which led to a recovery efficiency two (2) to three (3) times greater. Although the increase in recovery was smaller for the more viscous HydroCal oil, however, the recovery efficiency increased by 50%. At a spot thickness of

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10 mm, the recovery efficiency of HydroCal was lower than that of Endicott. This can be explained by the increase in the viscosity of HydroCal at 10-15 ° C. In such a small stain thickness, the water comes into contact with the drum and the total contact area between the oil and the drum is reduced. The more viscous HydroCal could not be distributed as fast as the Endicott did and had less access to the drum, which led to greater

5 amount of free water recovered, thereby reducing total recovery efficiency.

The effect of the temperature and the thickness of the oil spill on the recovery efficiency is illustrated in Figure 39. At an oil thickness of 10 mm, the temperature had no significant effect on the recovery rates of the smooth drums. During the second tests (at 10 ° C-15 ° C, which for simplicity is represented as 10 ° C in the graph), the corrugated drums had recovery rates similar to the smooth drums. The recovery rates of the corrugated drums during the Phase 1 tests (at 25-30 ° C, which for simplicity is represented as 25 ° C in the graph), were significantly higher. The temperature change did not have a significant effect on the recovery rates of 25 mm smooth drums. At a film thickness of 25 mm, the corrugated drums were considerably more efficient than the smooth drums,

15 although its efficiency was greater than 25 ° C.

Figure 40 shows the effect of oil type and temperature on the recovery efficiency of aluminum drums. The decrease in temperature led to a slight increase in Endicott's recovery rates by smooth drums, while it had no significant effect on HydroCal's recovery rates.

20 The decrease in temperature caused an increase in the viscosity of the test oils, which leads to a significant increase in the amount of Endicott recovered by the corrugated drums, while the HydroCal recovery rates were reduced somewhat.

Through previous experiments, it was discovered that: 25

(to)

The use of a ribbed pattern can increase recovery efficiency by 100-200%. The ribbed pattern proved efficient even in Diesel, which is difficult to recover due to its low viscosity.

(b)

The recovery efficiency of the corrugated surface can be improved by adapting the dimensions of the

30 grooves to oil properties. The use of more superficial and narrow grooves for light diesel and fuel, and deeper and more open grooves for heavier oils, can lead to even greater increase in recovery efficiency.

(c) The selection of the recovery surface material can increase the recovery efficiency by 35-20%.

(d) The recovery efficiency depends significantly on the type of petroleum product and is typically proportional to its viscosity (when the oil is at a temperature above its pour point).

40

(e) The oil spill thickness has a significant effect on recovery efficiency. The increase in oil thickness from 10 mm to 25 mm led to higher recovery rates. The increase in oil thickness from 25 to 50 mm did not significantly increase recovery rates. The amount of free water recovered was typically greater for an oil thickness of 10 mm than for the oil thickness of 25 or 50 mm.

Four. Five

(f) It was found that lowering the temperature increased recovery rates by increasing the viscosity of the oil and allowing a thicker black tide to remain on the recovery surface after removal. HydroCal recovered using a corrugated surface was the only exception. As the temperature dropped, the viscosity of the HydroCal reached a point where the oil did not penetrate deep enough

50 in the grooves leading to a smaller amount of recovered oil.

(g) The speed of rotation of the drum had a significant effect on recovery efficiency. For a skimmer and drum type tested, 40 rpm seemed to be an almost optimal rotation speed in most cases. Beyond 40 rpm, the drum began to recover significant amounts of free water. Without

55 However, it should be noted that free water was the only limiting factor. If a response team does not deal with the free water in the recovered product, the maximum rotation speed should be used to recover more oil.

It will be appreciated from the above description, that the grooved geometry of the invention is applicable to drum, disc, skimmer or belt type skimmers or other types of skimmers or other devices that

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they have a rotary fluid recovery unit to come in contact and collect oil or other liquids

viscous During use, the liquid recovery unit is placed in a viscous liquid body and rotated.

This puts the surface of the liquid recovery unit in contact with the viscous liquid body.

When the surface of the liquid recovery unit rotates out (for example, it is removed from) the body of the

5 viscous liquid, a quantity of the viscous liquid adheres to the recovery surface. Once the surface

Recovery is removed, scraped to remove the collected viscous liquid. The grooved geometry of the

The present invention helps retain the viscous liquid, thereby separating the viscous liquid from water or other

liquid. Accordingly, the claimed invention provides both liquid separation and recovery.

of the liquid In addition, the invention is applicable to the removal of oil from water, coconut oil from coconut juice, 10 or any other viscous liquid that is floating in, mixed with, or otherwise carried by a host liquid.

from which the viscous liquid will be separated and recovered.

Table 1. The effect of a groove angle on the surface

Angle of surface grooves

Surface (mm2) - ribbed side

180º - flat surface

1453

90º grooves

2005

60º grooves

2896

30º grooves

4663

Table 2. Properties of the oils used in Ohmsett field tests

Density at 15 ° C (g / ml)

Viscosity at 15 ° C (cP) % of asphaltenes

Diesel

0.833 6 0

Endicott

0.915 84 4

HydroCal 300

0.906 340 0

Claims (9)

1. An apparatus for the recovery of a viscous liquid, comprising: 5 (a) a rotary liquid recovery unit (10, 30); said liquid recovery unit (10, 30) having a surface with a pattern of a plurality of V-shaped grooves (14); said grooves (14) configured to collect and retain a viscous liquid (32) that comes into contact with said surface; Y

(b)

 a scraper (26) having an edge geometry complementary to said grooves (14), arranged to remove the retained viscous liquid from the surface of said liquid recovery unit (10, 30)

(C); the apparatus being characterized in that said grooves (14) are defined by walls having a separation angle of approximately sixty degrees or less.

An apparatus as recited in claim 1, wherein said liquid recovery unit comprises a drum-type, belt-type or disc-type liquid recovery unit.

3. An apparatus as cited in claim 1, wherein said grooves have a depth of 127 mm (five inches) or less. twenty 4. An apparatus as recited in claim 3, wherein said grooves have a depth of 25.4 mm (one inch) or less. 5. An apparatus as cited in claim 1: 25

(to)

 wherein said liquid recovery unit (10, 30) has a first and second ends;

(b)

wherein said liquid said liquid recovery unit (10, 30) has a longitudinal central axis that is

extends between said first and second ends; 30

(C)

 wherein said liquid recovery unit (10, 30) has a central radial axis that is orthogonal to said longitudinal axis;

(d)

wherein said grooves (14) substantially align with said central radial axis, or wherein said

35 grooves move angularly from said central radial axis at an angle less than approximately ninety degrees. 6. A method for recovering a viscous liquid, comprising: 40 (a) providing a liquid recovery unit having a surface with a pattern of a plurality of V-shaped grooves; said grooves configured to collect and retain a viscous liquid that comes into contact with said surface; 45 (b) disposing a scraper (26) having an edge geometry complementary to said grooves (14) to remove the viscous liquid retained from the surface of said liquid recovery unit (10, 30); (c) placing the surface of said liquid recovery unit in contact with a viscous liquid body, rotating said liquid recovery unit, and removing said liquid recovery unit from said viscous liquid body 50; (d) collecting the viscous liquid on the surface of said liquid recovery unit with said scraper; the procedure being characterized in that said grooves are defined by walls having a separation angle of approximately sixty degrees or less. 55

7.

A method as recited in claim 6, wherein said liquid recovery unit comprises a drum-type, belt-type or disc-type liquid recovery unit.

8.

A method as cited in claim 6, wherein said grooves have a

fifteen depth of 127 mm (five inches) or less. 9. A method as cited in claim 8, wherein said grooves have a depth of 25.4 mm (one inch) or less. 5 10. A method as cited in claim 6: (a) wherein said liquid recovery unit has a first and second ends; 10 (b) wherein said liquid recovery unit has a longitudinal central axis that extends between said first and second ends; (c) wherein said liquid recovery unit has a central radial axis that is orthogonal to said axis longitudinal; fifteen (d) wherein said grooves substantially align with said central radial axis; or wherein said grooves move angularly from said central radial axis at an angle less than about ninety degrees. 16